i was looking up a list of skyrim powers and found Polymorph Skeever but what is it?

A Red Dwarf easter egg, or the ability to turn into a skeever. Take your pick.

During the development of Skyrim Bethesda made an attempt at Polymorphing but ended up scrapping the idea. This is the outcome. Within the game using console commands you can obtain an un used power to transform into a Skeever. The camera appears under you (The skeever) in third person and in first person its still uses the human height for the view.
Source:uesp wikia

wow, that's cool, hopefully they'll think about adding that in a future dlc or a modder might pick it up

That is awesome.